The present invention relates to a semiconductor component and a method of manufacturing the same, in particular, the present invention relates to a transistor wherein the electric field is reduced (controlled) in the active region (channel) in critical areas using field plates and thereby the electric field is distributed more uniformly along the component, whereby the power of the component can be improved.
Field plates are usually employed in a large selection of semiconductor components like HEMTs, MISFETs, MOSFETs etc. The field plates are required to control the electric field in critical areas (channel) and thereby accomplish certain component characteristics (e.g. greater breakdown strength or improved linearity). The electric field is distributed more uniformly along the component (channel), whereby the power of the component can be reduced.
Field plates can be combined with different potential sources and electrodes or can stand alone without being connected to a defined potential (so-called “unearthed”, “floating” or “free-of-ground”). Although field plates are useful for reducing electric field gradients, they have a fundamental disadvantage in that they increase the capacitances of the component and deteriorate the power in the high-frequency region since they lead to a reduced cutoff frequency due to the increased component capacitance.
A uniform field plate (i.e. exactly one field plate disposed in the area of the channel), for example a field effect transistor with a uniform field plate connected to the gate potential, generates two separate peaks of the electric field along the channel, one peak being near the drain-side edge and the other peak being near the gate-side edge of the drain electrode. This means that the field in the component is still highly concentrated locally and exhibits very high absolute values. To overcome this problem and smooth the field peaks, two field plates stacked on top of each other have been proposed in US 2005/0253168 and in X. Huili et al. (“High breakdown voltage AlGaN—GaN HEMTs achieved by multiple field plates,” Electron Component Letters, IEEE, vol. 25, no. 4, pp. 161-163, 2004).
A disadvantage of the stacked field plates proposed in the state of the art is the high manufacturing cost of the component due to the large number of necessary process steps as well as the error-proneness due to the necessity of a very exact alignment of the field plates to each other.